Interaction of toroidal focal conic defects with shear flow

Chatterjee, Sourav; Anna, Shelley L.

doi:10.1039/c2sm07377c

Cited by 6 publications

(8 citation statements)

References 34 publications

(70 reference statements)

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“…In this section, we explain our results in the non-equilibrium FCD formation when the system is subjected to shear stress-quench from high to low values [ 18 ]. Some studies on the FCD formation behavior under shear have been also reported [ 73 , 74 ].…”

Section: Fcd Formation Induced By Shear Quenchmentioning

confidence: 99%

Structural Rheology of the Smectic Phase

Fujii

Komura

2014

Materials

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In this review article, we discuss the rheological properties of the thermotropic smectic liquid crystal 8CB with focal conic domains (FCDs) from the viewpoint of structural rheology. It is known that the unbinding of the dislocation loops in the smectic phase drives the smectic-nematic transition. Here we discuss how the unbinding of the dislocation loops affects the evolution of the FCD size, linear and nonlinear rheological behaviors of the smectic phase. By studying the FCD formation from the perpendicularly oriented smectic layers, we also argue that dislocations play a key role in the structural development in layered systems. Furthermore, similarities in the rheological behavior between the FCDs in the smectic phase and the onion structures in the lyotropic lamellar phase suggest that these systems share a common physical origin for the elasticity.

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Section: Fcd Formation Induced By Shear Quenchmentioning

confidence: 99%

Structural Rheology of the Smectic Phase

Fujii

Komura

2014

Materials

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“…25 The experimental picture up to date is broad and well understood on a macroscopic length scale. [27][28][29] Additionally, theoretical approaches such as elasticity theory capture the experimental picture adequately. 21,30 Moreover, the interest in equilibrium 31,32 and nonequilibrium 33,34 properties of LC confined to mesoscopic or even nanoscopic geometries has grown in the past years.…”

Section: Introductionmentioning

confidence: 99%

A novel model for smectic liquid crystals: Elastic anisotropy and response to a steady-state flow

Püschel-Schlotthauer

Turrión

Stieger

et al. 2016

The Journal of Chemical Physics

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By means of a combination of equilibrium Monte Carlo and molecular dynamics simulations and nonequilibrium molecular dynamics we investigate the ordered, uniaxial phases (i.e., nematic and smectic A) of a model liquid crystal. We characterize equilibrium behavior through their diffusive behavior and elastic properties. As one approaches the equilibrium isotropic-nematic phase transition, diffusion becomes anisotropic in that self-diffusion D in the direction orthogonal to a molecule's long axis is more hindered than self-diffusion D in the direction parallel to that axis. Close to nematic-smectic A phase transition the opposite is true, D < D. The Frank elastic constants K, K, and K for the respective splay, twist, and bend deformations of the director field n̂ are no longer equal and exhibit a temperature dependence observed experimentally for cyanobiphenyls. Under nonequilibrium conditions, a pressure gradient applied to the smectic A phase generates Poiseuille-like or plug flow depending on whether the convective velocity is parallel or orthogonal to the plane of smectic layers. We find that in Poiseuille-like flow the viscosity of the smectic A phase is higher than in plug flow. This can be rationalized via the velocity-field component in the direction of the flow. In a sufficiently strong flow these smectic layers are not destroyed but significantly bent.

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“…Very recently, Chatterjee and Anna studied the effects of shear and dilation ows on toroidal and parabolic FCD formations. 11,12 They showed that the critical dilation required for parabolic FCD formation increases under shear ow because such ow annihilates dislocations.…”

Section: Discussionmentioning

confidence: 99%

“…When shear ow is applied to a smectic phase, non-equilibrium dislocations and textural defects such as focal conic domains (FCDs) are formed, which signicantly inuence the smectic rheology. [1][2][3][4][5][6][7][8][9][10][11][12] Defect-mediated rheology in the smectic phase is an important issue in structural rheology, which deals with the ow properties inuenced by meso-scale structures in so matter. 13 Defects and dislocations affect both rheological responses and dynamic phase behaviors of so matter.…”

Section: Introductionmentioning

confidence: 99%

Structural rheology of focal conic domains: a stress-quench experiment

Fujii

Komura

2014

Soft Matter

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We study the dynamics of focal conic domain (FCD) formation in a thermotropic smectic phase under shear stress. It is known that increasing the shear stress induces a non-equilibrium phase transition from a smectic phase with FCDs (SmAI) to another smectic phase (SmAII) in which the layers are oriented. By quenching the shear stress from the SmAII phase to the SmAI phase, we find three characteristic modes in the FCD formation process. The first mode is attributed to the edge dislocation dynamics induced by climb motions. The second mode results from FCD formation. The first and second modes show slowing down close to the smectic-nematic transition temperature, implying that the dynamics are dominated by dislocation unbinding. The third mode originates from the alignment of FCDs which form oily streaks. Such an alignment occurs when the shear stress balances the line tension of the oily streaks.

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Interaction of toroidal focal conic defects with shear flow

Cited by 6 publications

References 34 publications

Structural Rheology of the Smectic Phase

Structural Rheology of the Smectic Phase

A novel model for smectic liquid crystals: Elastic anisotropy and response to a steady-state flow

Structural rheology of focal conic domains: a stress-quench experiment

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